| 摘要 |
PURPOSE:To detect the etching finish point of a non photo transmitting film on a photo transmitting substrate by detecting the variation of amounts of light emitted from the end surface of said substrate. CONSTITUTION:A Cr film on the glass plate 1 is etched via a resist mask by means of gas plasma. At this time, focusing lens is arranged in opposition to the side surface A of the glass plate 1, and an optical fiber is connected thereto. Then, the Cr film 10 is etched and plasma light B comes incident and is emitted from the side surface A, thus being led to a photomultiplier 8. By this constitution, the Cr film is etched in a fixed time after starting etching, and the etching does not further advance. Therefore, the emitted light from the side surface is saturated at a constant value, and the amount of light does not increase, accordingly the etching finish point is easily made clear. |
